Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior. The description adds useful operational context beyond annotations: x402 pricing, Solana payment, an HTTPS endpoint, and that zero moduli are rejected. It does not fully describe payment failure or error behavior, but it is substantially transparent.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded: the mathematical operation comes first, followed by examples, validation rules, range, and payment/access details. Every sentence provides relevant information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple pure mathematical function with no output schema, the description is complete enough: it defines the operation, bounds, modulus semantics, examples, pricing, and endpoint. Safety behavior is already covered by annotations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must carry parameter meaning. It explains that n ranges from 0 to 512 and that mod must be a positive decimal integer with zero rejected, supported by examples; it omits the 600-digit modulus cap and does not define the hexanacci recurrence, but otherwise compensates well.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States the specific operation clearly: H(n) mod m for the hexanacci numbers. The examples and domain constraints make it distinguishable from sibling tools such as hexanacci, hexanacci_step, and hexanacci_sum.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The use case is implied by the name and operation, and the description gives n/mod constraints plus examples. However, it does not explicitly say when to use this modulo variant instead of sibling tools like hexanacci or hexanacci_sum.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.